Top Endocrine Publications of 2012: Canine and Feline Endocrine Nutrition

In my 11th and last compilation of canine and feline endocrine publications of 2012, I’m finishing up with endocrine nutrition and treatment of obesity in dogs and cats. Starting in February of 2014, I'm planning to start posting the endocrine publications for 2013. I'm only waiting for the final papers published in December to come out so they can be included in my lists and reviews.

Listed below are 31 research papers written in 2012 that deal with a variety of topics concerning endocrine nutrition or obesity in the dog and cat. Remember that adipose tissue is the largest endocrine gland in the body, making a number of hormones, including leptin, adiponectin, and resistin. These hormones generally influence energy metabolism, which is of great interest to the understanding and treatment of type 2 diabetes and obesity.

These papers range from the studies of the effects of calcium deficiency in growing and adult dogs (1) to studies of the effect of dietary fat intake on circulating lipids in cats (2); from cause, prevalence, and management of obesity in dogs and cats (3,4,12-16,21,25-27,30) to the effect of nutrition on calcium oxalate and calcium excretion in cats (7,8); and from the effects on dietary L-carnitine supplementation on metabolism in cats (4) to the changes in fat-free mass and leptin in hyperthyroid cats before and after treatment (11,18).

Other research studies include the influence of dietary composition on the circulating glucose and insulin response to feeding (9,10) to factors that regulate serum leptin and adiponectin concentrations in dogs and cats (12,20,21,23) and studies of the role of dietary selenium and iodine on nutrition and metabolism (22,31). Finally, this lists also includes a excellent paper on dietary hyperthyroidism in dogs (19) — where we are reminded that not all dogs with thyrotoxicosis have a hyperfunctioning thyroid carcinoma!

2012 Papers on Endocrine Nutrition and Obesity:

1. Becker N, Kienzle E, Dobenecker B. Calcium deficiency: a problem in growing and adult dogs: two case reports. Tierarztl Prax Ausg K Kleintiere Heimtiere 2012;40:135-139. 
2. Butterwick RF, Salt C, Watson TD. Effects of increases in dietary fat intake on plasma lipid and lipoprotein cholesterol concentrations and associated enzyme activities in cats. Am J Vet Res 2012;73:62-67. 
3. Cave NJ, Allan FJ, Schokkenbroek SL, et al. A cross-sectional study to compare changes in the prevalence and risk factors for feline obesity between 1993 and 2007 in New Zealand. Prev Vet Med 2012;107:121-133. 
4. Center SA, Warner KL, Randolph JF, et al. Influence of dietary supplementation with l-carnitine on metabolic rate, fatty acid oxidation, body condition, and weight loss in overweight cats. Am J Vet Res 2012;73:1002-1015. 
5. Clark MH, Hoenig M, Ferguson DC, et al. Pharmacokinetics of pioglitazone in lean and obese cats. J Vet Pharmacol Ther 2012;35:428-436. 
6. Corbee RJ, Tryfonidou MA, Meij BP, et al. Vitamin D status before and after hypophysectomy in dogs with pituitary-dependent hypercortisolism. Domest Anim Endocrinol 2012;42:43-49. 
7. Dijcker JC, Hagen-Plantinga EA, Everts H, et al. Dietary and animal-related factors associated with the rate of urinary oxalate and calcium excretion in dogs and cats. Vet Rec 2012;171:46. 
8. Dijcker JC, Kummeling A, Hagen-Plantinga EA, et al. Urinary oxalate and calcium excretion by dogs and cats diagnosed with calcium oxalate urolithiasis. Vet Rec 2012;171:646. 
9. Elliott KF, Rand JS, Fleeman LM, et al. A diet lower in digestible carbohydrate results in lower postprandial glucose concentrations compared with a traditional canine diabetes diet and an adult maintenance diet in healthy dogs. Res Vet Sci 2012;93:288-295. 
10. Farrow H, Rand JS, Morton JM, et al. Postprandial glycemia in cats fed a moderate carbohydrate meal persists for a median of 12 hours -- female cats have higher peak glucose concentrations. J Feline Med Surg 2012;14:706-705. 
11. Finch NC, Welsh CP, Hibbert A. Changes in fat-free mass (FFM) in cats undergoing radioactive iodine therapy. J Feline Med Surg 2012;14:652-653.
12. German AJ. Barking up the wrong tree: what's the deal with obesity, adiponectin and inflammation in dogs? Vet J 2012;194:272-273.
13. German AJ, Holden SL, Morris PJ, et al. Long-term follow-up after weight management in obese dogs: the role of diet in preventing regain. Vet J 2012;192:65-70. 
14. German AJ, Holden SL, Wiseman-Orr ML, et al. Quality of life is reduced in obese dogs but improves after successful weight loss. Vet J 2012;192:428-434. 
15. Haring T, Haase B, Zini E, et al. Overweight and impaired insulin sensitivity present in growing cats. J Anim Physiol Anim Nutr (Berl) 2012; doi: 10.1111/j.1439-0396.2012.01322.x. 
16. Hoenig M. The cat as a model for human obesity and diabetes. J Diabetes Sci Technol 2012;6:525-533. 
17. Hutchinson D, Freeman LM, McCarthy R, et al. Seizures and severe nutrient deficiencies in a puppy fed a homemade diet. J Am Vet Med Assoc 2012;241:477-483. 
18. Jaillardon L, Burger M, Siliart B. Leptin levels in hyperthyroid cats before and after treatment. Vet Rec 2012;170:155. 
19. Köhler B, Stengel D, Neiger R. Dietary hyperthyroidism in dogs. J Small Anim Pract 2012;53:182-184. 
20. Mazaki-Tovi M, Abood SK, Schenck PA. Effect of omega-3 polyunsaturated fatty acids and body condition on serum concentrations of adipokines in healthy dogs. Am J Vet Res 2012;73:1273-1281. 
21. Ricci R, Bevilacqua F. The potential role of leptin and adiponectin in obesity: a comparative review. Vet J 2012;191:292-298. 
22. Todd SE, Thomas DG, Bosch G, et al. Selenium status in adult cats and dogs fed high levels of dietary inorganic and organic selenium. J Anim Sci 2012;90:2549-2555. 
23. Tvarijonaviciute A, Ceron JJ, Martinez-Subiela S, et al. Serum and urinary adiponectin in dogs with renal disease from leishmaniasis. Vet Rec 2012;171:297. 
24. Tvarijonaviciute A, German AJ, Martinez-Subiela S, et al. Analytical performance of commercially-available assays for feline insulin-like growth factor 1 (IGF-1), adiponectin and ghrelin measurements. J Feline Med Surg 2012;14:138-146. 
25. Tvarijonaviciute A, Ceron JJ, Holden SL, et al. Obesity-related metabolic dysfunction in dogs: a comparison with human metabolic syndrome. BMC Vet Res 2012;8:147. h
26. Tvarijonaviciute A, Tecles F, Martinez-Subiela S, et al. Effect of weight loss on inflammatory biomarkers in obese dogs. Vet J 2012;193570-572. 
27. Tvarijonaviciute A, Ceron JJ, Holden SL, et al. Effects of weight loss in obese cats on biochemical analytes related to inflammation and glucose homeostasis. Domest Anim Endocrinol 2012;42:129-141. 
28. Verbrugghe A, Hesta M, Daminet S, et al. Nutritional modulation of insulin resistance in the true carnivorous cat: a review. Crit Rev Food Sci Nutr 2012;52:172-182. 
29. Verkest KR, Fleeman LM, Morton JM, et al. Association of postprandial serum triglyceride concentration and serum canine pancreatic lipase immunoreactivity in overweight and obese dogs. J Vet Intern Med 2012;26:46-53. 
30. Verkest KR, Rand JS, Fleeman LM, et al. Spontaneously obese dogs exhibit greater postprandial glucose, triglyceride, and insulin concentrations than lean dogs. Domest Anim Endocrinol 2012;42:103-112.
31. Zicker S, B. S. Focus on nutrition: the role of iodine in nutrition and metabolism. Compendium 2012;34:E1-E4. 

Obesity Epidemic Expanding in Dogs and Cats

The rates of overweight and obesity in dogs and cats in the U.S. continued to increase in 2012, with the number of overweight cats reaching an all-time high.

Results of the sixth annual National Pet Obesity Awareness Day Survey, conducted by the Association for Pet Obesity Prevention (APOP), revealed that 52.5% of dogs and 58.3% of cats were overweight or obese (Figure 1). That equals approximately 80 million U.S. dogs and cats at increased risk for weight-related disorders such as diabetes, osteoarthritis, hypertension, and many cancers.

Figure 1. Incidence of overweight and obesity in cats and dogs (from APOP website).

As Dr. Ernie Ward, APOP’s founder and lead veterinarian for the survey states. “Pet obesity remains the leading health threat to our nation’s pets. We continue to see an escalation in the number of overweight cats and an explosion in the number of type 2 diabetes cases.”

And veterinary endocrinologist and APOP board member Dr. Mark Peterson agrees: “The soaring rate of feline and canine obesity is taking a terrible toll on our animals’ health. There is a vast population of overweight cats and dogs facing an epidemic of diabetes. The best preventive measure a pet owner can make is to keep their dog or cat at a healthy weight. Diabetes is far easier to prevent than treat, especially when twice daily insulin injections are needed.”

For more information about the 2012 National Pet Obesity survey results or the Association for Pet Obesity Prevention in general, please visit their website at www.petobesityprevention.com.

Top Endocrine Publications of 2011: Canine and Feline Endocrine Nutrition

In my 10th and last compilation of the canine and feline endocrine publications of 2011, I’m finishing up with endocrine nutrition and treatment of obesity in dogs and cats. Starting in February of the New Year, I'm planning to start posting the endocrine publications for 2012. I'm only waiting for the final papers published in December to come out so they can be included in my lists and reviews.

Listed below are 27 research papers written in 2011 that deal with a variety of topics of clinical importance concerning endocrine nutrition or obesity in the dog and cat. Remember that adipose tissue is the largest endocrine gland in the body, making a number of hormones, including leptin, adiponectin, and resistin. These hormones generally influence energy metabolism, which is of great interest to the understanding and treatment of type 2 diabetes and obesity.

These papers range from the studies of the effects of neutering on body weight and body composition in cats (1,2) to studies of the glucose intolerance and insulin resistance associated with obesity (3, 20-22); from the cause, prevalence, and management of obesity in dogs and cats (5,8-10,25,26) to the effect of nutrition and dietary water on calcium oxalate and stuvite in cats (4,7).

Other research studies include the influence of dietary composition on the circulating glucose and insulin response to feeding (6,11-13) to factors that regulate serum leptin and adiponectin concentrations in dogs and cats (16-18,22-24). Finally, this lists also includes two excellent review papers on feline nutrition (15,27) — where we are reminded that cats are true carnivores and need higher amounts of protein, and not carbs!

References:

1. Alexander LG, Salt C, Thomas G, et al. Effects of neuteringon food intake, body weight and body composition in growing female kittens. Br J Nutr 2011;106 Suppl 1:S19-23. 
2. Backus R. Plasma oestrogen changes in adult male cats afterorchiectomy, body-weight gain and low-dosage oestradiol administration. Br J Nutr 2011;106 Suppl 1:S15-18. 
3. Brunetto MA, Sa FC, Nogueira SP, et al. The intravenous glucose tolerance and postprandial glucose tests may present different responses in the evaluation of obese dogs. Br J Nutr 2011;106 Suppl 1:S194-197. 
4. Buckley CM, Hawthorne A, Colyer A, et al. Effect of dietary water intake on urinary output, specific gravity and relative supersaturation for calcium oxalate and struvite in the cat. Br J Nutr 2011;106 Suppl 1:S128-130. 
5. Chauvet A, Laclair J, Elliott DA, et al. Incorporation of exercise, using an underwater treadmill, and active client education into a weight management program for obese dogs. Can Vet J 2011;52:491-496. 
6. Coradini M, Rand JS, Morton JM, et al. Effects of twocommercially available feline diets on glucose and insulin concentrations,insulin sensitivity and energetic efficiency of weight gain. Br J Nutr 2011;106 Suppl 1:S64-77. 
7. Dijcker JC, Plantinga EA, van Baal J, et al. Influence ofnutrition on feline calcium oxalate urolithiasis with emphasis on endogenousoxalate synthesis. Nutr Res Rev 2011:1-15. 
8. German AJ. Canine obesity--weighing on the mind of the owner? J Small Anim Pract 2011;52:619-620. 
9. German AJ, Holden SL, Gernon LJ, et al. Do feeding practices of obese dogs, before weight loss, affect the success of weight management? Br J Nutr 2011;106 Suppl 1:S97-100. 
10. German AJ, Holden SL, Mather NJ, et al. Low-maintenance energy requirements of obese dogs after weight loss. Br J Nutr 2011;106 Suppl 1:S93-96. 
11. Hewson-Hughes AK, Gilham MS, Upton S, et al. Postprandialglucose and insulin profiles following a glucose-loaded meal in cats and dogs. Br J Nutr 2011;106 Suppl 1:S101-104. 
12. Hewson-Hughes AK, Gilham MS, Upton S, et al. The effect ofdietary starch level on postprandial glucose and insulin concentrations in catsand dogs. Br J Nutr 2011;106 Suppl 1:S105-109.
13. Hoenig M, Jordan ET, Glushka J, et al. Effect of macronutrients, age, and obesity on 6- and 24-h postprandial glucose metabolism in cats. Am J Physiol Regul Integr Comp Physiol 2011;301:R1798-1807. 
14. Ryan VH, Trayhurn P, Hunter L, et al. 11-Hydroxy-beta-steroid dehydrogenase gene expression in canine adipose tissue and adipocytes: stimulation by lipopolysaccharide and tumor necrosis factor alpha. Domest Anim Endocrinol 2011;41:150-161. 
15. Sparkes AH. Feeding old cats—an update on new nutritional therapies. Top Companion Anim Med 2011;26:37-42. 
16. Tan HY, Rand JS, Morton JM, et al. Adiponectin profiles areaffected by chronic and acute changes in carbohydrate intake in healthy cats. General & Comparative Endocrinology 2011;172:468-474. 
17.  Tvarijonaviciute A, Ceron JJ, Martinez-Subiela S. Assessment of five ELISAs for measurement of leptin concentrations in dogs. Am J Vet Res 2011;72:169-173. 
18. Tvarijonaviciute A, Eralp O, Kocaturk M, et al. Adiponectin and IGF-1 are negative acute phase proteins in a dog model of acute endotoxaemia. Vet Immunol Immunopathol 2011;140:147-151. 
19. Tvarijonaviciute A, Tecles F, Carillo JM, et al. Serum insulin-like growth factor-1 measurements in dogs: performance characteristics of an automated assay and study of some sources of variation. Can J Vet Res 2011;75:312-316. 
20. Verkest KR, Fleeman LM, Morton JM, et al. Compensation for obesity-induced insulin resistance in dogs: assessment of the effects of leptin, adiponectin, and glucagon-like peptide-1 using path analysis. Domest Anim Endocrinol 2011;41:24-34. 
21. Verkest KR, Fleeman LM, Rand JS, et al. Evaluation of beta-cell sensitivity to glucose and first-phase insulin secretion in obese dogs. Am J Vet Res 2011;72:357-366. 
22. Verkest KR, Rand JS, Fleeman LM, et al. Distinct adiponectin profiles might contribute to differences in susceptibility to type 2 diabetes in dogs and humans. Domest Anim Endocrinol 2011;41:67-73. 
23. Verkest KR, Rose FJ, Fleeman LM, et al. Adiposity and adiponectin in dogs: investigation of causes of discrepant results between two studies. Domest Anim Endocrinol 2011;41:35-41. 
24. Wakshlag JJ, Struble AM, Levine CB, et al. The effects of weight loss on adipokines and markers of inflammation in dogs. Br J Nutr 2011;106 Suppl 1:S11-14. 
25. Warren BS, Wakshlag JJ, Maley M, et al. Use of pedometers to measure the relationship of dog walking to body condition score in obese and non-obese dogs. Br J Nutr 2011;106 Suppl 1:S85-89. 
26. White GA, Hobson-West P, Cobb K, et al. Canine obesity: is there a difference between veterinarian and owner perception? J Small Anim Pract 2011;52:622-626. 
27. Zoran DL, Buffington CA. Effects of nutrition choices and lifestyle changes on the well-being of cats, a carnivore that has moved indoors. J Am Vet Med Assoc 2011;239:596-606. 

High Protein, Low Carb Diets: Key to Management of Obesity in Cats

As in humans, obesity is a major problem in cats in this country. Unfortunately, the feline obesity epidemic appears to be getting worse, rather than better (1,2). Many veterinarians and cat owners who have tried traditional feline weight loss diets (generally high fiber/low fat) have found this approach frustrating, since it usually fails to achieve significant loss of weight.

Another approach in treating and preventing feline overweight and obesity revolves around our understanding of basic feline nutritional needs and their feeding behavior (1-7). The way we feed our cats and what we feed them tend to violate all principles of "ideal" feline nutrition.

Indoor cats are commonly fed energy-dense, high-carbohydrate dry foods in a free choice manner, which provides the cat with much more energy than he or she can possible use. Outdoor cats in the wild must maintain fitness, and therefore a lean body weight, in order to successfully hunt for food. Such fitness is not required in sedentary, indoor cats, and they take advantage of the highly-palatable food that is readily available, without any undue physical effort to sustain. Free access to plentiful amounts of cat food plus little physical activity leads to overweight and obesity in cats, as in other species (5-8).

Obesity and the Composition of the Diet
One important factor that is important to consider, both in the development of and treatment of obesity, is the role of carbohydrates (carbs) in the diet – not because carbs themselves are directly associated with fat (although excess carbs are stored as fat), but because of the effect on protein levels in the diet.

The higher the concentration of carbs in the diet, the lower the intake of protein. This can result in a lower-than-needed intake of protein for maintenance and energy. We can never forget that cats are evolutionary designs to use protein and fat preferentially as energy sources (3,4). Cats have absolutely no requirement for any carbs in their diet.

Because of the metabolic requirement for cats to utilize protein as an energy source, diets with modest amounts of protein (with an average digestibility) can result in loss of muscle mass or sarcopenia (6,7,9-11). The loss of lean muscle mass leads to a lowering of the metabolic rate and can make weight gain even worse!

Traditional Weight Loss Diets Lead to Muscle Wasting
Traditional weight loss plans include feeding an energy restricted (e.g., low-fat, high-carbohydrate, high-fiber) diet. However, while these diets may result in weight loss, they do so to the detriment of lean body mass— especially in cats who use protein for energy even in the face of other energy sources in the diet.

Successful weight loss regimens requires loss of adipose tissue as well as maintenance of lean body mass (5-7). We must remember that lean body mass is the driver of basal energy metabolism (loss of lean body mass is a major contributor to weight regain as appetite is not reduced and satiety not reached).

Feeding High Protein, Low Carb Diet Best
Several recent studies have evaluated use of a high-protein, low-carbohydrate diet (protein 45% or higher) for weight loss in cats (5-7,12,13). In those studies, cats lost weight but maintained lean body mass. Importantly, high-protein, low-carbohydrate canned diets not only result in sustained weight loss in these cats, but also will help reduce the cat's urge to eat constantly. This is simply because the cats are more likely to be satiated when feeding a canned food versus a dry food with fiber.

Because dry foods must be extruded (i.e., made into a biscuit), carbohydrates are required in the cooking process. Thus, it is difficult to achieve a low-carbohydrate diet that is dry. Further, many of the available high-protein, low-carbohydrate dry foods are NOT low-calorie foods, so it is extremely easy to feed too much. Too many calories, including too many protein calories, will also cause weight gain or failure to lose weight, as well (6,7,14).

At this time, the best commercial diets for achieving a high protein, low carbohydrate profile, along with controlled calories, are canned foods. But it is important to remember that just because you are feeding a canned food, it does NOT mean that you are feeding a high-protein, low-carbohydrate diet (you must read the label), and it also doesn’t mean you are feeding a high-quality protein.

Stop Free-Choice Feeding
An important follow up point to remember about all diets is that calories count. You cannot "free choice" feed most indoor cats—even with high protein, low carb diets— because if they consume too many calories, they will become or remain obese.

The daily allotment of food should be fed in multiple small meals to mimic the cat's natural feeding strategy of hunting and catching about 10 small prey animals per day. This also increases the thermal effect of food, which increases the metabolic rate and assists in weight loss.

Calculating Calories for Weight Reduction in Cats
One key point for obesity prevention (or correction) is balancing the energy intake/energy expenditure equation. In indoor cats, where exercise is reduced by the nature of the lifestyle, energy restriction becomes paramount to obesity prevention or correction (5-7). Most indoor cats do not need more than their resting energy requirement (RER) to meet their daily nutritional requirements (this is approximately 180-200 kcal/day for a 10-11 pound cat).

Cats that are very obese will likely need to reduce their intake by 20% to 40% (or 60-80% of their RER) to lose weight (5-7). So, for a cat that is 16 pounds (7.5 kg) that should weigh 11 pounds (5 kg), it may require a reduction of calories to only 120-130 kcal/day. It is much more difficult to reduce calories using dry food rather than canned food because of the small amount of kibble that must be fed.

The key point is this: set a target calorie intake, make sure you are feeding a high protein food to protect muscle mass and prevent protein malnutrition, then weigh the cat monthly, and adjust the amount of food based on weight loss.

The Bottom Line
Energy restriction can be achieved by low-fat, high-fiber diets, but most of those diets are not high enough in protein to preserve muscle.  Such loss of muscle mass results in an unhealthy weight loss and a strong tendency to regain weight (i.e., the loss of muscle mass will always increase the likelihood of rapid regain of lost weight or failure of weight loss).

High-protein, low-carbohydrate, low-fat diets are ideal for weight loss in cats: they help preserve muscle mass while restricting energy sources that will induce fat loss. However, portion control is ultimately the key to controlling energy intake.

The easiest way to both feed a high-protein, low-carbohydrate diet while achieving portion control is to feed canned food. In cats that won’t eat canned food, there are only a few high-protein, low-fat, low-carb dry foods – but these should be selected for use in weight loss programs only when absolutely needed.

References:

1. Zoran DL. Obesity in dogs and cats: a metabolic and endocrine disorder. Veterinary Clinics of North America Small Animal Practice 2010 Mar;40:221-39
2. Zoran DL, Buffington CAT. Effects of nutritional factors and lifestyle choice on the health and well-being of indoor cats. Journal of the American Veterinary Medical Association 2011;239:596-606. 
3. Zoran DL. The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association 2002;221:1559-1567. 
4. Zoran DL. The unique nutritional needs of the cat. In: Ettinger SJ, Feldman EC (eds). Textbook of Veterinary Internal Medicine, 7th edition. Saunders Elsevier, 2010;652-659. 
5. Laflamme DP. Understanding and managing obesity in dogs and cats. Veterinary Clinics of North America Small Animal Practice 2006;36:1283-1295. 
6. Zoran DL. Feline obesity: recognition and management. Compendium for Continuing Education for the Practicing Veterinarian 2009;31:284-293. 
7. Zoran DL. Protein: the key to metabolism, health, and management of obesity in cats. 2012 OVMA Conference Proceedings. http://www.ovma.org/pdf/sa_program_clinicalpearls.pdf
8. Harper EJ, Stack DM, Watson TD, et al. Effects of feeding regimens on bodyweight, composition and condition score in cats following ovariohysterectomy. J Small Anim Pract 2001;42:433-438. 
9. Hannah SS, LaFlamme DP. Effect of dietary protein on nitrogen balance and lean body mass in cats. Veterinary Clinical Nutrition 1996;3:30. 
10. Perez-Camargo G. Cat nutrition: What is new in the old? Compendium for Continuing Education for the Practicing Veterinarian 2004;26 (Suppl 2A):5-10. 
11. Wakshlag JJ. Dietary protein consumption in the healthy aging companion animal. Proceedings of the Nestlé Purina Companion Animal Nutrition Summit: Focus on Gerontology 2010;32-39.
12. Vasconcellos RS, Borges NC, Goncalves KN, et al. Protein intake during weight loss influences the energy required for weight loss and maintenance in cats. Journal of Nutrition 2009;139:855-860.   
13. Nguyen P, Leray V, Dumon H, et al. High protein intake affects lean body mass but not energy expenditure in nonobese neutered cats. Journal of Nutrition 2004;134:2084S-2086S. 
14. Wei A, Fascetti AJ, Liu KJ, et al. Influence of a high-protein diet on energy balance in obese cats allowed ad libitum access to food. Journal of Animal Physiology and Animal Nutrition 2011;95:359-367.      

Diet Composition: The Key to Management of Obesity in Cats

Importance of Obesity as a Disease

Obese humans generally do not live as long as their lean counterparts, and are much more likely to suffer from obesity-related diseases such as type II diabetes, coronary artery disease, osteoarthritis, hypertension, and some cancers. Cats are susceptible to the many of the same detrimental effects, including decreased longevity, orthopedic disease, diabetes, and cancer (1-3).

It has been estimated that up to a third of cats are overweight or grossly obese, with the highest rates seen in middle-aged cats (4,5). However, owners may not recognize that their cat is overweight, nor be aware of the associated health risks.

Obesity, a Major Endocrine Disease!

The expansion of adipose tissue was long thought to be simply a depot for the deposition of fatty acids (triglycerides) that occurred because of the excess energy intake (see Figure 1a).

However, research in the past decade has revealed that adipose tissue is not just a storage site, but also is responsible for production of many key hormones (e.g. leptin and adipokines) involved in energy balance and a variety of other processes (Figure 1b).

In other words, adipose tissue turns out to be an endocrine gland — in fact, its the largest endocrine gland in the body, secreting the largest number of obesity hormones (3,6,7)!

What does this mean for the obese cat? Obesity is a metabolic disease that results in major changes in appetite control (they are more hungry), energy expenditure (their metabolic rate is lower, thus they need to eat less), and induces a chronic, low-grade, pro-inflammatory state that may be responsible for many of the diseases associated with increased body weight (3,6-8)

Feline Obesity and Its Causes

The primary reason for development of obesity in any animal is that they are consuming more energy than they are expending. This can occur when a cat has excessive dietary intake of calories (e.g., high energy density food, excess food or treats offered) or when there is a reduction in energy expenditure (e.g., lower metabolism due to body weight or muscle mass, neuter status, or reduced activity, or illness or injury resulting in less exercise).

Recent studies indicate that greater than a third of all cats in the United States and Europe are obese, and this number likely underestimates the depth and breadth of the problem (3-5). There are a number of factors that contribute to feline obesity, including the following:

• Sex and neuter status (male vs. female; intact vs. castrated or spayed). Neutering is an important risk factor due to the hormonal changes that occur that result in changes in levels of leptin, progestins, and other hormones that result in increased appetite, and reduced energy metabolism and metabolic rate (9-11). The key factors for prevention of obesity in neutered animals appears to be careful control of intake immediately after neutering (no free choice feeding, reduction of intake by 25% to account for the hormonal changes resulting in reduced energy needs), and close monitoring of body weight and BCS to allow adjustments in intake if needed (3,11-13).

• Activity (indoor vs. outdoor). In indoor cats, reduced energy expenditure is a very important problem, and this is compounded by the fact that it is not easy to increase energy expenditure in cats like dogs with directed exercise (2,3,12,13).

• Feeding style (meal feeding vs free choice; canned vs dry food). When feeding free choice dry food, the risk of overfeeding, even in very small amounts is very high (2,3,12,13). In either case, the primary reason that weight gain occurs in cats is that they have a positive energy balance and this must be changed to affect weight loss.

Prevention is key here. As we all know, it is much harder to take the pounds off than it is to put them on.

Obesity and the Composition of the Diet: Frequently Ignored

Another factor that is important to consider, both in the development and treatment of obesity, is the role of carbohydrates (carbs) in the diet – not because carbs themselves are directly associated with fat (although excess carbs are stored as fat), but because of the effect on protein levels in the diet (13-15).

The higher the concentration of carbs in the diet, the lower the intake of protein. This results in a lower-than-needed intake of protein for maintenance and energy.

In my next post, we'll continue this topic of obesity in cats, and discuss why low carb, higher protein diets may be the best.

References:

1. Zoran DL, Buffington CAT. Effects of nutritional factors and lifestyle choice on the health and well-being of indoor cats. Journal of the American Veterinary Medical Association 2011;239:596-606. 
2. Laflamme DP. Understanding and managing obesity in dogs and cats. Veterinary Clinics of North America Small Animal Practice 2006;36:1283-1295. 
3. Zoran DL. Obesity in dogs and cats: a metabolic and endocrine disorder. Veterinary Clinics of North America Small Animal Practice 2010;40:221-239.
4. Courcier EA, O'Higgins R, Mellor DJ, et al. Prevalence and risk factors for feline obesity in a first opinion practice in Glasgow, Scotland. Journal of Feline Medicine and Surgery 2010;12:746-753. 
5. Colliard L, Paragon BM, Lemuet B, et al. Prevalence and risk factors of obesity in an urban population of healthy cats. Journal of Feline Medicine and Surgery 2009;11:135-140. 
6. Lusby AL, Kirk CA, Bartges JW. The role of key adipokines in obesity and insulin resistance in cats. Journal of the American Veterinary Medical Association 2009;235:518-522. 
7. Kil DY, Swanson KS. Endocrinology of obesity. Veterinary Clinics of North America Small Animal Practice 2010;40:205-219. 
8. German AJ, Ryan VH, German AC, et al. Obesity, its associated disorders and the role of inflammatory adipokines in companion animals. Veterinary Journal 2010;185:4-9. 
9. Martin L, Siliart B, Dumon H, et al. Leptin, body fat content and energy expenditure in intact and gonadectomized adult cats: a preliminary study. Journal of Animal Physiology and Animal Nutrition 2001;85:195-199. 
10. Alexander LG, Salt C, Thomas G, et al. Effects of neutering on food intake, body weight and body composition in growing female kittens. British Journal of Nutrition 2011;106 Suppl 1:S19-23. 
11. Mitsuhashi Y, Chamberlin AJ, Bigley KE, et al. Maintenance energy requirement determination of cats after spaying. British Journal of Nutrition 2011;106 Suppl 1:S135-138. 
12. Michel K, Scherk M. From problem to success: feline weight loss programs that work.  Journal of Feline Medicine and Surgery 2012;14:327-336. 
13. Zoran DL. Protein: the key to metabolism, health, and management of obesity in cats. 2012 OVMA Conference Proceedings. http://www.ovma.org/pdf/sa_program_clinicalpearls.pdf 
14. Vasconcellos RS, Borges NC, Goncalves KN, et al. Protein intake during weight loss influences the energy required for weight loss and maintenance in cats. Journal of Nutrition 2009;139:855-860. 
15. Wei A, Fascetti AJ, Liu KJ, et al. Influence of a high-protein diet on energy balance in obese cats allowed ad libitum access to food. Journal of Animal Physiology and Animal Nutrition 2011;95:359-367.

Q & A: Should High Protein, Low Carbohydrate Diets Be Fed to All Cats?

I have recently read more and more information about feeding diabetic cats a canned food that contains a low carbohydrate content. By low, I mean a diet that contains less than 10% carbohydrate, ideally closer to 5%.

Do you agree? If so, what about feeding normal cats? Should I recommend a canned cat food that has less than 10% carbohydrate for most cats in general? Would this help reduce the frequency of fat or diabetic cats or both in my practice?

My Response:

This is a very controversial area, but I do believe that diabetic cats should be fed a low carbohydrate, high protein diet and most endocrinologists agree (1). Lowering the carbohydrate level in cats with diabetes mellitus improves their insulin sensitivity and makes them easier to regulate. And some cats will even go into diabetic remission on the low-carbohydrate diets.

From there, I don't think it's much of a leap to ask —why do we wait until cats become diabetic to feed them differently? To me, it makes a great deal of sense to feed normal cats a diet composition close to what they would be getting in the wild. That would be a diet composed of approximately 50-60% protein, 5-10% carbohydrates, and 30-50% fat (2-4).

A Cat's Natural Diet in the Wild

Cats are true obligate carnivores (5-11). This means they must eat meat to survive; cats cannot be vegetarians. Put another way, cats are meant to consume animal-based proteins (meat), not plant-based proteins (grains).

Why should we pay attention to what a cat would eat in the wild? Because cats, at least compared to dogs, really aren't that domesticated as far as their nutritional needs are concerned (5). Domestication has changed feline metabolism very little. Historically, we have valued them for their hunting abilities (controlling rodents). It is only recently that we have tried to feed cats a processed, carbohydrate-filled diet. It is no coincidence that this same period also exhibited a dramatic increase in obesity and a multitude of diseases, including diabetes and hyperthyroidism (10,11).

In the wild, cats eat whole, raw prey. Their diet includes small rodents (e.g, mice, rats), rabbits, birds, insects, and amphibians (5-10,11). They usually eat the whole animal, including the meat, bones, brains, and organs. Their systems are uniquely set up to metabolize this diet which is high in moisture, high in protein, and very low in carbohydrates. Because this is the diet they have relied upon for tens of thousands of years, they do not have the ability to process carbohydrates very efficiently. Cats get most of their energy requirements from the glucose their livers process from protein, not carbohydrates (7,8,10).

Of course, cats in the wild do not eat corn, soybeans, rice, or grains as part of their daily meal. But that's exactly what we are asking our cats to eat when we feed them many of the commercial foods we recommend every day — why would we continue to feed cats plant-based diets better suited for omnivores?

Determining the Composition of Cat Food Diets

Composition refers to the breakdown of the 3 basic food components  — protein, fats, and carbohydrates.

The most accurate way to evaluate pets foods and their composition is to consider the calories or metabolizable energy (ME) that come from the protein, fat, and carbohydrate fractions (12). This allows us to compare various diets without worrying about their different water (moisture) levels. I find it very confusing to calculate the value of an individual nutrients when expressed as a percentage of food weight (as fed) or as a percentage of dry matter (dry matter basis)

Check out this website (http://binkyspage.tripod.com/foodfaq.html), which gives you a breakdown of the composition of the various prescription and over-the-counter diets. Remember that we'd like a diet that provides less than 10% of calories from carbohydrates and around 50% of calories from protein. It turns out that many of the over-the-counter diets have a better composition of protein and carbohydrates than you might have thought — even better than many of the more expensive prescription diets.

When looking at caloric distribution (instead of food weight), you can compare canned and dry foods on a fairly equal level. Notice that the composition of almost all dry food cat diets are much too high in carbohydrates and most are too low in protein content. That is why I believe it's best to limit the amount of dry food that is fed to cats, or even better, not feed dry food at all.

The Cat Food Ingredient List

Once we find a diet with the composition that is acceptable, we also have to look at the ingredient list of the food (13). Not all of the proteins in cat foods are equal in quality.  Remember that quality meat is the best ingredient in a food and that meat byproducts is a close second; but vegetable and grains may supply a less bioavailable form of protein for cats.

All ingredients are required to be listed in order of predominance by weight. The weights of ingredients are determined as they are added in the formulation, including their inherent water content. This latter fact is important when evaluating relative quantity claims, especially when ingredients of different moisture contents are compared.

Look at the ingredient list supplied by the manufacturer. If the first ingredient is meat, the label should say so. If the first ingredient is a "byproduct" (unrendered parts of an animal left over after slaughter) remember this can include heads, feet, intestines, feathers, and egg shells. Even thought this may not be very pleasing to think about eating yourself,  remember that cats do not share in people's aesthetic concerns about the source and composition of their food.

Cat foods with meat byproducts as a first ingredient are still much better than foods that lists grains (e.g., corn, corn gluten meal, or rice) as a first ingredient. The main ingredients in a carnivore's diet shouldn't be grain, it should be animal protein.

For more information on understanding labels, visit the FDA's website on interpreting pet food labels:
http://www.fda.gov/animalveterinary/resourcesforyou/ucm047113.htm

Feeding Your Cat: The Bottom Line

Cats have gone from frequent consumption of small meals that consisted of animals they could catch and kill, to consumption of prepared diets of human choosing, which are often available in excessive amounts.  In addition, the composition of the diets fed do not match the high protein/ low carbohydrate ratio than is found in wild birds, insects, and small rodents.

As a result, there is increasing evidence that many of the chronic health problems of domestic cats, including obesity, diabetes, and probably hyperthyroidism,  are directly or indirectly related to nutrition or lifestyle changes that have been imposed on them by their owners (10, 11).

Let's use some common sense and feed cats foods that are closer in composition to what they are best designed to eat.

References:

1. Rucinsky R, Cook A, Haley S, Nelson R, Zoran DL, Poundstone M. AAHA diabetes management guidelines for dogs and cats. Journal of the American Animal Hospital Association 2010; 46:215-24.
2. Myrcha A, Pinowski J. Weights, body composition and caloric value of post-juvenile molting European tree sparrows. Condor 1970;72:175–178.
3. Vondruska JF. The effect of a rat carcass diet on the urinary pH of the cat. Companion Animal Practice 1987;1:5-9.
4. Crissey SD, Slifka KA, Lintzenich BA. Whole body cholesterol, fat, and fatty acid concentrations of mice (Mus domesticus) used as a food source. Journal of Zoo and Wildlife Medicine 1999;30:222-227.
5. Driscoll CA, Clutton-Brock J, Kitchener AC, et al. The Evolution of House Cats: Genetic and archaeological findings hint that wildcats became house cats earlier—and in a different place—than previously thought. Scientific America June 10, 2009.
6. Kirk CA, Debraekeleer J, Armstrong PJ. Normal cats In: Hand MS, Thatcher CD, Remillard RL, et al., eds. Small Animal Clinical Nutrition. 4th Edition ed. Philadelphia: W.B. Saunders, 2000;291-351.
7. MacDonald ML, Rogers QR, Morris JG. Nutrition of the domestic cat, a mammalian carnivore. Annual Review of Nutrition 1984;4:521-562.
8. Morris JG. Idiosyncratic nutrient requirements of cats appear to be diet-induced evolutionary adaptations. Nutrition Research Reviews 2002;15:153-168.
9. Zaghini G, Biagi G. Nutritional peculiarities and diet palatability in the cat. Veterinary Research Communications 2005;29, Suppl 2:39-44
10. Zoran DL. The carnivore connection to nutrition in cats. Journal of the American Veterinary Medical Association 2002;221:1559-1567.
11. Zoran DL, Buffington CA. Effects of nutrition choices and lifestyle changes on the well-being of cats, a carnivore that has moved indoors. Journal of the American Veterinary Medical Association 2011;239:596-606.
12. Laflamme DP. Determining metabolizable energy content in commercial pet foods. Journal of Animal Physiolology and Animal Nutrition (Berlin). 2001; 85:222-230.
13. Thompson A. Ingredients: where pet food starts. Topics in Companion Animal Medicine 2008;23:127-132.

Pet Diets and Nutrition: Helpful Links

Nutrition and diet plays a huge role in management of many, if not most, endocrine disorders affecting dogs and cats—just consider diabetes mellitus, hyperlipidemia, Cushing's syndrome, and hyper- and hypothyroidism.

If you are like me, you didn't have a nutrition class during your veterinary training, at least one that had anything to do with canine or feline nutrion. And even if you did have a class, it's very likely that you may have slept through most of it, and you need nutrition help from time to time. If that is the case, you're not alone!

Below I've listed some links to websites that deals with various issues of nutrition, nutrion consultant services for vets and/or the pet owner, and tools to help in dogs and cats with obesity to help with weight loss. I've also included a section on home cooking and BARF (biologically appropriate raw food) diets since many of our clients ask us their use.

Nutrition Services for Veterinarians:

• American College of Veterinary Nutrition (help to find a veterinary nutritionist)
• Pet Diet Nutrition Consults
• Nutrition Support Service, University of California Davis
• Nutrition Support Service, Ohio State University
• Clinical Nutrition Program, University of California – San Diego
• University of Tennessee Veterinary Nutrition Service
• University of Missouri Clinical Nutrition Service
• Tufts University Clinical Nutrition Veterinary Specialty

Pet Nutrition Sites for Pet Owners Interested in Home Cooked Diets:

• Pet Diets
• BalanceIT
• Nutrition Support Service, Ohio State University

Obesity/Weight Loss Sites:

• Association for Pet Obesity Prevention (APOP)
• Pet-to-Human Weight Equivalent Charts
• Calorie Calculators
• Calorie Content Database Searcher

FDA Center for Food Safety and Applied Nutrition:

• Bad Bug Book — a refresher on "bad bugs" that can be found in pet food

Feeding Raw or BARF Diets (Biologically Appropriate Raw Food):

• Raw Learning (pro-BARF perspective)
• Barf World (another pro-BARF perspective)
• FDA: Is it safe for me to provide my pet with a raw food diet?
• Center for Veterinary Medicine Offers Advice on Raw Meat Diets
• Center for Veterinary Medicine Issues Draft Guidance on Raw Meat Diets
• FDA Issues Final Guidance on Raw Meat for Animals
• FDA Tips for Preventing Foodborne Illness Associated with Pet Food & Pet Treats
• Feline Nutrition Education Society
• Making Cat Food: CatInfo.org

Food Recalls, Market Withdrawals, And Safety Alerts:

• Recalls, Market Withdrawals, & Safety Alerts
• Recalls & Withdrawals

Nutrition Tools and Calculators:

• Guaranteed Analysis Convertor
• Energy Requirement Calculator
• Binky's Nutrition Page (carbohydrate & protein content in cat canned/dry foods)

Other Informative Sites for Cats:

• Binky's Nutrition Page (carbohydrate & protein content in cat canned/dry foods)
• Feeding Your Cat: Know the Basics of Feline Nutrition
• Cat Nutrition
• Feline Nutrition Education Society

Top Endocrine Publications of 2010: The Canine and Feline Obesity

In my 10th and last compilation of the canine and feline endocrine publications of 2010, I’m finishing up with obesity disorders of dogs and cats. Surprised? Well, it turns out that adipose tissue is the largest endocrine gland in the body, making a number of hormones, including leptin, adiponectin, and resistin. These hormones generally influence energy metabolism, which is of great interest to the understanding and treatment of type 2 diabetes and obesity.

Listed below are 36 research papers written in 2010 that deal with a variety of topics of issues of clinical importance concerning obesity in the dog and cat.

These range from the studies of the cause, prevalence, and management of obesity (1-3,6,16,17,24,27,36) to the relationship been weight and survival (5) and lameness (18); from studies of noninvasive methods for estimating the percent body fat in dogs and cats (7,15) to the role inflammatory adipokines play in obese animals (8,13,28); and from studies of hypertriglyceridemia and hyperlipidemia in dogs and cats (10,12,14,34) to studies of the endocrinology of animal obesity (8,13,17).

References:

1. Bland IM, Guthrie-Jones A, Taylor RD, et al. Dog obesity: veterinary practices' and owners' opinions on cause and management. Preventive Veterinary Medicine 2010;94:310-315.
2. Courcier EA, O'Higgins R, Mellor DJ, et al. Prevalence and risk factors for feline obesity in a first opinion practice in Glasgow, Scotland. Journal of Feline Medicine and Surgery 2010;12:746-753.
3. Courcier EA, Thomson RM, Mellor DJ, et al. An epidemiological study of environmental factors associated with canine obesity. The Journal of Small Animal Practice 2010;51:362-367.
4. Fernandez-Real JM, Ortega F, Gomez-Ambrosi J, et al. Circulating osteocalcin concentrations are associated with parameters of liver fat infiltration and increase in parallel to decreased liver enzymes after weight loss. Osteoporosis International 2010;21:2101-2107.
5. Finn E, Freeman LM, Rush JE, et al. The relationship between body weight, body condition, and survival in cats with heart failure. Journal of Veterinary Internal Medicine 2010;24:1369-1374.
6. German AJ, Holden SL, Bissot T, et al. A high protein high fibre diet improves weight loss in obese dogs. Veterinary Journal 2010;183:294-297.
7. German AJ, Holden SL, Morris PJ, et al. Comparison of a bioimpedance monitor with dual-energy x-ray absorptiometry for noninvasive estimation of percentage body fat in dogs. American Journal of Veterinary Research 2010;71:393-398.
8. German AJ, Ryan VH, German AC, et al. Obesity, its associated disorders and the role of inflammatory adipokines in companion animals. Veterinary Journal 2010;185:4-9.
9. Gilor C, Graves TK, Lascelles BD, et al. The effects of body weight, body condition score, sex, and age on serum fructosamine concentrations in clinically healthy cats. Veterinary Clinical Pathology 2010;39:322-328.
10. Hatano Y, Mori N, Asada M, et al. Hypertriglyceridemia with increased plasma insulin concentrations in cats. Research in Veterinary Science 2010;88:458-460.
11. Hoenig M, Jordan ET, Ferguson DC, et al. Oral glucose leads to a differential response in glucose, insulin, and GLP-1 in lean versus obese cats. Domestic Animal Endocrinology 2010;38:95-102.
12. Jeusette I, Torre C, Salas A, et al. Effects of consuming diets containing various fats or citrus flavanones on plasma lipid and urinary F2-isoprostane concentrations in overweight cats. American Journal of Veterinary Research 2010;71:1039-1044.
13. Kil DY, Swanson KS. Endocrinology of obesity. The Veterinary Clinics of North America: Small Animal Practice 2010;40:205-219.
14. Kluger EK, Caslake M, Baral RM, et al. Preliminary post-prandial studies of Burmese cats with elevated triglyceride concentrations and/or presumed lipid aqueous. Journal of Feline Medicine and Surgery 2010;12:621-630.
15. Lee H, Kim M, Choi M, et al. Assessment of feline abdominal adipose tissue using computed tomography. Journal of Feline Medicine and Surgery 2010;12:936-941.
16. Linder DE, Freeman LM. Evaluation of calorie density and feeding directions for commercially available diets designed for weight loss in dogs and cats. Journal of the American Veterinary Medical Association 2010;236:74-77.
17. Lubbs DC, Vester Boler BM, Ridge TK, et al. Dietary macronutrients and feeding frequency affect fasting and postprandial concentrations of hormones involved in appetite regulation in adult dogs. Journal of Animal Science 2010;88:3945-3953.
18. Marshall WG, Hazewinkel HA, Mullen D, et al. The effect of weight loss on lameness in obese dogs with osteoarthritis. Veterinary Research Communications 2010;34:241-253.
19. Martin LJ, Siliart B, Lutz TA, et al. Postprandial response of plasma insulin, amylin and acylated ghrelin to various test meals in lean and obese cats. The British Journal of Nutrition 2010;103:1610-1619.
20. Mitsuhashi Y, Nagaoka D, Ishioka K, et al. Postprandial lipid-related metabolites are altered in dogs fed dietary diacylglycerol and low glycemic index starch during weight loss. The Journal of Nutrition 2010;140:1815-1823.
21. Muranaka S, Mori N, Hatano Y, et al. Obesity induced changes to plasma adiponectin concentration and cholesterol lipoprotein composition profile in cats. Research in Veterinary Science 2010.
22. Newhall K, Nunamaker E, Gissendanner S, et al. CB-1 antagonism with LY2190416 results in acute weight loss in obese adult dogs fed a high-fat diet. Journal of Veterinary Pharmacology and Therapeutics 2010;33:615-618.
23. Nieminen P, Rouvinen-Watt K, Kapiainen S, et al. Molecular evolution of adiponectin in Carnivora and its mRNA expression in relation to hepatic lipidosis. General and Comparative Endocrinology 2010;168:307-311.
24. Nijland ML, Stam F, Seidell JC. Overweight in dogs, but not in cats, is related to overweight in their owners. Public Health Nutrition 2010;13:102-106.
25. Nishii N, Yamasaki M, Takasu M, et al. Plasma leptin concentration in dogs with diabetes mellitus. The Journal of Veterinary Medical Science 2010;72:809-811.
26. Piccione G, Giudice E, Fazio F, et al. Association between obesity and reduced body temperature in dogs. International Journal of Obesity 2010.
27. Rohlf VI, Toukhsati S, Coleman GJ, et al. Dog obesity: can dog caregivers' (owners') feeding and exercise intentions and behaviors be predicted from attitudes? Journal of Applied Animal Welfare Science 2010;13:213-236.
28. Ryan VH, German AJ, Wood IS, et al. Adipokine expression and secretion by canine adipocytes: Stimulation of inflammatory adipokine production by LPS and TNF alpha. Pflugers Archivive 2010;460:603-616.
29. Sieber-Ruckstuhl NS, Zini E, Osto M, et al. Effect of hyperlipidemia on 11beta-hydroxysteroid-dehydrogenase, glucocorticoid receptor, and leptin expression in insulin-sensitive tissues of cats. Domestic Animal Endocrinology 2010;39:222-230.
30. Slavov E, Georgiev IP, Dzhelebov P, et al. High-fat feeding and Staphylococcus intermedius infection impair beta cell function and insulin sensitivity in mongrel dogs. Veterinary Research Communications 2010;34:205-215.
31. Tvarijonaviciute A, Martinez-Subiela S, Ceron JJ. Validation of 2 commercially available enzyme-linked immunosorbent assays for adiponectin determination in canine serum samples. Canadian Journal of Veterinary Research 2010;74:279-285.
32. Tvarijonaviciute A, Tecles F, Ceron JJ. Relationship between serum butyrylcholinesterase and obesity in dogs: a preliminary report. Veterinary Journal 2010;186:197-200.
33. Verbrugghe A, Hesta M, Van Weyenberg S, et al. The glucose and insulin response to isoenergetic reduction of dietary energy sources in a true carnivore: the domestic cat ( Felis catus). The British Journal of Nutrition 2010;104:214-221.
34. Xenoulis PG, Steiner JM. Lipid metabolism and hyperlipidemia in dogs. Veterinary journal 2010;183:12-21.
35. Zini E, Osto M, Konrad D, et al. 10-day hyperlipidemic clamp in cats: effects on insulin sensitivity, inflammation, and glucose metabolism-related genes. Hormone and Metabolic Research 2010;42:340-347.
36. Zoran DL. Obesity in dogs and cats: A metabolic and endocrine disorder. The Veterinary Clinics of North America: Small Animal Practice 2010;40:221-239.